# crc32
Standard CRC-32 algorithm implementation in JS (for the browser and nodejs).
Emphasis on correctness and performance.
## Installation
With [npm](https://www.npmjs.org/package/crc-32):
$ npm install crc-32
In the browser:
The script will manipulate `module.exports` if available (e.g. in a CommonJS
`require` context). This is not always desirable. To prevent the behavior,
define `DO_NOT_EXPORT_CRC`
## Usage
In all cases, the relevant function takes a single argument representing data.
The return value is a signed 32-bit integer.
- `CRC32.buf(byte array or buffer)` assumes the argument is a set of 8-bit
unsigned integers (e.g. nodejs `Buffer` or simple array of ints).
- `CRC32.bstr(binary string)` interprets the argument as a binary string where
the `i`-th byte is the low byte of the UCS-2 char: `str.charCodeAt(i) & 0xFF`
- `CRC32.str(string)` interprets the argument as a standard JS string
For example:
```js
> // var CRC32 = require('crc-32'); // uncomment this line if in node
> CRC32.str("SheetJS") // -1647298270
> CRC32.bstr("SheetJS") // -1647298270
> CRC32.buf([ 83, 104, 101, 101, 116, 74, 83 ]) // -1647298270
> [CRC32.str("\u2603"), CRC32.str("\u0003")] // [ -1743909036, 1259060791 ]
> [CRC32.bstr("\u2603"), CRC32.bstr("\u0003")] // [ 1259060791, 1259060791 ]
> [CRC32.buf([0x2603]), CRC32.buf([0x0003])] // [ 1259060791, 1259060791 ]
```
## Testing
`make test` will run the node-based tests.
To run the in-browser tests, run a local server and go to the `ctest` directory.
To update the browser artifacts, run `make ctest`.
`make baseline` will generate baseline files based on the unicode mapping at
## License
Please consult the attached LICENSE file for details. All rights not explicitly
granted by the Apache 2.0 license are reserved by the Original Author.
## Badges
[](https://travis-ci.org/SheetJS/js-crc32)
[](https://coveralls.io/r/SheetJS/js-crc32?branch=master)
[](https://github.com/SheetJS/js-crc32)